Richard Broadhead, Senior Field Application Scientist at Quantum Si, introduced Platinum Pro, a tool designed to sequence proteins and single amino acid resolution. This benchtop system helps detect proteins through direct interaction with the amino acids.
The sequencing process involves sample preparation, loading peptides onto a microfluidic chip, and running the Platinum Pro machine. Then the data is uploaded to a cloud-based analysis system for sequence output.
The first step deploys Lys-C to digest the proteins, this works by cutting the lysine and functionalises the peptides by creating a C-terminal lysine. Next a linker is added which links to the C-terminal lysine at one end and the other end binds to the microfluidic chip using a streptavidin biotin reaction. There is minimal hands-on-requirements making the platform very easy to use.
The recogniser molecule will bind to the amino acid generating a full pulse of fluorescence and the length of time or the duration of that pulse is determined by the identity of the amino acid being sequenced. The sequence data or raw fluorescence data is converted into a protein sequence. By observing changes in pulse duration during sequencing, the system can detect PTMs. Although, the software is being fine-tuned with the hopes that it can automatically identify specific PTMs. Furthermore, no dedicated computer is required for this, everything is done on the cloud making it highly user friendly and results and reports are accessible beyond the lab setting.
The Platinum Pro system often detects peptides not seen in mass spectrometry workflows, making it a complementary tool for protein analysis. For example, these systems can distinguish between leucine and isoleucine which is usually difficult because the two amino acids are isobaric. The pulse duration for leucine and isoleucine are 0.38 and 0.24 respectively, this is because the kinetics of the on/off binding are different. Whereas MS may struggle to pick up on this. The system directly interacts with amino acids and is precise in detecting variations on a single amino acid level: it can detect changes at the RNA level.
Broadhead also discussed the protein barcoding workflow which is becoming increasingly prominent in the life sciences industry. Protein barcoding detects and quantifies proteins that are difficult to sequence directly, such as in nanobody enrichment and therapeutic mRNA delivery using lipid nanoparticles. He said: “So rather than sequencing the protein of interest directly, what you would do is sequence this barcode, which essentially acts as a proxy for your protein as a reporter sequence.”
